This invention relates generally to lighting ballasts, and more particularly to improved ballasts for high intensity discharge lighting devices.
Some types of electric lighting devices, such as gaseous discharge lamps, require electrical power of a different type than is normally available directly from electric utility mains. Furthermore, such devices often require electrical power of a different type for starting up than for maintaining illumination once started. In addition, certain operational benefits derive from varying the characteristics of the electrical power provided from a ballast to a lamp.
Many types of lamps powered by ballasts generate, as an inherent aspect of their operation, significant amounts of heat as well as light. In most applications, this heat is not desired and is considered waste, thus reducing the overall efficiency of the lighting system of which the lamp forms a part.
Depending on the application desired, ballasts may be needed that operate on different mains input voltages, phases, frequencies and the like. Further, depending on the application desired, ballasts may be needed that provide different electrical characteristics to the lamps they are driving. As a result, ballast providers must stock a large number of different parts (or “SKUs”), each of which must be separately ordered and inventoried. The large variety of ballasts needed for common applications thus requires electrical equipment suppliers to maintain an inventory of many parts, some of which may sit unsold for a long time, thus using warehouse space in a less than optimal manner.
Known disclosures, such as U.S. Pat. No. 7,129,647, have described some efforts to address some of the aforementioned issues, but a need remains for improved control of the electricity provided to lamps using a programmable ballast.